I needed to add sortable columns to clients wordpress for custom meta data I created so I used a pre_user_query hook

add_action('pre_user_query', 'user_column_orderby');

function user_column_orderby($user_search) {
    global $wpdb, $current_screen;

    if ( 'users' != $current_screen->id )

    $vars = $user_search->query_vars;

    if('Kön' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='gender')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];
    } elseif ('Ålder' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='age')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];
    } elseif ('Distrikt' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='district')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];
    } elseif ('Kategori' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='category')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];

This works fine if you're on the user screen. But I also added a export to csv button, which calls my export-csv.php file that looks like this:

$location = $_SERVER['DOCUMENT_ROOT'];
include ($location . '/wp-load.php');

if (current_user_can('manage_options')) {
    header("Content-type: application/force-download");
    header('Content-Disposition: inline; filename="users'.date('YmdHis').'.csv"');

    // WP_User_Query arguments
    $args = array (
        'order'          => 'ASC',
        'orderby'        => 'display_name',
        'fields'         => 'all',

    // The User Query
    $blogusers = get_users( 'orderby=nicename&order=ASC' );
    // Array of WP_User objects.
    foreach ( $blogusers as $user ) {
        //echo '<span>' . esc_html( $user->user_email ) . '</span>';

Now, the problem I'm having is that my .csv file has a notice:

Notice: Trying to get property of non-object in .../wp-content/themes/mytheme/admin/users_additionals.php on line 133

Which points to the line:

if ( 'users' != $current_screen->id )

in my first code. This happens because I've hooked to the pre_user_query hook, and I'm querying users in my file. Is there a way to suppress this notice (without going to wp-config.php and removing the debug code - this is not the solution, just masking the problem)?

  • Loading WordPres in a external file is not a good practice instead you can hook the whole code on some action!
    – Sumit
    Apr 6, 2016 at 9:16
  • Yeah, I was wondering how to do that as well :\ I'm exporting the file by clicking on the button which calls this file. In it are the headers that force the download, I don't know which action to use here. Any advice is helpful
    – dingo_d
    Apr 6, 2016 at 9:53

1 Answer 1


'users' != $current_screen->id in your file $current_screen is not set therefore, you are getting warning.

You can pass custom var in your user query and check before running your code.

$blogusers = get_users( 'orderby=nicename&order=ASC&my_filter=1' ); 

Here we are passing my_filter=1 then later we can check in pre_user_query

global $wpdb, $current_screen;

$vars = $user_search->query_vars;

if (isset($current_screen->id) && 'users' != $current_screen->id) {
} else if (empty($vars['myfilter'])) {

However, loading WordPress in a external file is not a good thing. Instead of external file you can wrap the whole code in a function and hook it on some action where headers are not sent.


Create a form instead of link e.g.

<form action="" method="POST">
    <input type="hidden" name="myprefix_export_csv" value="1" />
    <input type="submit" value="download" />

Then check if your custom key is set, if it is then export CSV with your current code.

add_action('init', 'export_csv'); //you can use admin_init as well
function export_csv() {
    if (!empty($_POST['myprefix_export_csv'])) {

        //Send headers
        //Query users
        //print data


You can also set nonce in form if you think other users can tweak it.

  • I need to have a button there, could I use the second code with the AJAX?
    – dingo_d
    Apr 6, 2016 at 10:29
  • I guess NO, you can send file in Ajax response.
    – Sumit
    Apr 6, 2016 at 10:32
  • I've placed the form, but the $_POST is empty on reload and when I click the button to send the form. Any idea why?
    – dingo_d
    Apr 6, 2016 at 10:37
  • 1
    Figured why: <input type="hidden" id="myprefix_export_csv" name="myprefix_export_csv" value="1" /> your input didn't have name set, and you've set the hidden as a name instead of type. Thanks!
    – dingo_d
    Apr 6, 2016 at 10:44

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